Living on the island of Ambon from the age of 25 until his death, Georg Everhard Rumphius (1627–1702) explored, experimented and wrote about the natural world of the Indies while working as a koopman for the United Dutch East Indies Company. His knowledge of the flora and fauna of the islands was best encapsulated in two of his now best-known works, Het Amboinsch Kruydboek and D’Amboinsche Rariteitkamer. This paper seeks to trace the information networks of this one man, whose writings projected an Ambonese world that was much larger than the tiny island of Ambon itself. How was Rumphius able to explore the natural world of the Indies through his engagement with local itinerant merchants and Muslim practitioners of medicine? What kinds of relationships did he establish with them and how did his experiences come to influence the scales of difference and similarity that he applied to his understanding of nature and the diversity of people living in the archipelago? Within the geographic and temporal contours of this study, circulation of knowledge did not exclusively take the form of a linear trajectory whereby knowledge was collected in the tropical fringes, changed in transit and consumed in the centre. Rather, through the example of Rumphius’ works, this paper demonstrates how ‘local’ knowledge produced through cross-cultural interactions underwent its own complicated circuits of transmission within the Indonesian archipelago before reaching a wider audience in Europe.